file = open('21.txt')
s = file.readline()
l = 1
kro = 0
koo = 0
krr = 0
ans = 0
for r in range(2, len(s)):
    if s[r-1:r+1] == 'RO':
        kro += 1
    if s[r-2:r+1] == 'ORO':
        koo += 1
    if s[r-2:r+1] == 'ROR':
        krr += 1
    while kro >= 21 and krr == 0 and koo == 0:
        if s[l-1:l+1] == 'RO':
            kro -= 1
        l += 1
    ans = max(ans, r - l + 1)
    if krr != 0 or koo != 0:
        l = r
        krr = 0
        koo = 0
print(ans)